Walker Percy won the 1961 National Book Award for this novel, his masterpiece, which unfolds in New Orleans during a momentous Carnival week. It's a great book that we can recommend as much for its sheer readability as for its literary merit and palpable sense of place. It's a particular treat for anyone who's been to New Orleans, though, for Percy ticks off street names and neighborhoods with the assiduity of a guidebook -- and considerably more soul.  (USS249, $13.95)